Heat oven to 350° F. Using a sharp paring knife, score the ham with lines ¼ inch deep and 1 inch apart, creating a diamond pattern (this will help the skin to crisp while cooking). Line a rimmed baking sheet with foil. Place the ham, skin-side up, on the prepared sheet and cover with foil.
In a food processor or blender, pulse rosemary, thyme, tarragon, orange peel, marjoram, lavender (if using), salt, peppercorns, and olive oil to make paste.
Rub the herb paste all over the skin, making sure to get inside the score marks. Bake until the skin is crispy and the ham is warmed through, about 1½ hours. Serve warm or at room temperature.